It has been widely known that sordes on teeth are difficultly removed from such portions as gum grooves among the teeth and pockets deep in the gum grooves. In order to remove sordes on teeth, in general, attempts have been made to conduct the brushing by so contriving the shape of bristle tips of a tooth brush that the bristles can be easily inserted in the gum grooves. With this method, however, a persevering manual work must be conducted for every portion requiring a brushing time of not less than one hour, and a person finds himself tired on his arm consuming too much time and finds it not easy to continue the work any longer.
To solve this problem, Japanese Patent No. 2663213 teaches a tooth-brushing device in which a cylindrical portion of a large diameter is formed in a water passage near the end of a water-injection nozzle, means is provided for reciprocally driving a piston body held in the cylindrical portion, whereby the end of a bundle of stiff bristles held on the front surface of the piston body is caused to reciprocally move in the direction of length of the bristles to go in and out of the blow-out port at the end of the nozzle.
With the system in which the end of the bundle of stiff bristles goes in and out of the blow-out port at the end of the nozzle in the direction of length of the bundle of stiff bristles, however, the moving distance of the bristle tips varies in the direction of length of the bristles. Therefore, it becomes highly probable that the bristle tips are stuck to the inflamed gum causing a severe pain not only when the patient brushes his teeth by himself but also when the patient has his teeth brushed by an expert such as a dentist.
It is therefore a first object of the present invention to realize a safe brushing without sticking the gum if the bristle tips are once inserted in a pocket of a tooth by using a system having a brush of which the bristle tips automatically vibrate in a direction at right angles with the direction of length of the bristles due to the flow of water.
A second object is to efficiently wash, out of the pocket, the sordes and foul matter peeled off the tooth surfaces due to the brushing by concentrating the water flow blown out from the nozzle onto the bristle tips of the brush.
A third object is to realize a safe brushing without sticking the gum if the bristle tips are once inserted in a pocket of a tooth by using a system having a brush that automatically revolves due to the flow of water.
A fourth object is to realize a safe brushing without sticking the gum if the bristle tips are once inserted in a pocket of a tooth by using a system having a brush of which the bristle tips automatically vibrate in a direction at right angles with the direction of length of the bristles due to the flow of water, the system having a simplified internal structure.